Forensic DNA typing was developed to improve our ability to conclusively identify an individual and distinguish that person from all others. Current DNA profiling techniques yield incredibly rare types, but definitive identification of one and only one individual using a DNA profile remains impossible. This fact may surprise you, as there is a popular misconception that a DNA profile is unique to an individual, with the exception of identical twins. You may be the only person in the world with your DNA profile, but we cannot know this short of typing everyone. What we can do is calculate probabilities. The result of a DNA profile translates into the probability that a person selected at random will have that same profile. In most cases, this probability is astonishingly tiny. Unfortunately, this probability is easily misinterpreted, a situation we will see and discuss many times in the coming chapters.

This Systematics Association Special Volume is the result of a symposium entitled, ‘Cryptic taxa - artefact of classification or evolutionary phenomena?’ held on June 17 as part of the Association’s 10th Biennial Meeting 2019. I began to realise that the notion of cryptic species touches the heart of several major debates in biology, including, ‘what are species?’, ‘how should we recognize them?’, the notion of punctuated equilibria and that of morphological stasis in the fossil record. Also, in the midst of a biodiversity crisis the phenomenon of cryptic species suggests that there may be a greater diversity of evolutionary lineages in need of conservation than has been suggested. The chapters that emerged from the Symposium show clearly how the topic of 'species' remains central to biodiversity sciences and the subject of wide-ranging and lively debate. In almost every chapter there is a call for change, either of direction or for the inclusion of new developments and data, and their focus ranges from abandoning species altogether to highlighting the weaknesses in current taxonomic process suggesting that our representation of the biological universe is still a chaotic torso.

This brief chapter introduces the book. The rationale, scope, and coverage are summarized, including mention of topics that are not covered. Aspects of debate, disagreement, and consensus in the field are summarized before the chapter is concluded with a look to future potential progress.

This chapter explains why I wrote this book and it provides an outline of each chapter. This book traces the history of the scientific discipline that I call narrative phylogenetics from its origin in the second half of the nineteenth century to today. Narrative phylogenetics is a storytelling discipline that is concerned with tracing the evolution of lineages, and it is driven by speculations about the evolutionary process and the evolutionary descent of characters from precursors in hypothetical ancestors. Although phylogenetics has developed enormously since then, narrative phylogenetic reasoning remains visible in the scientific debates of today.

The notion that our planet and its inhabitants have not remained exactly as the Creator was supposed to have made them was in the air long before 1859, when the English natural historian Charles Darwin collected and published his evolutionary ideas in his great work On the Origin of Species by Means of Natural Selection. By that time geologists had long known that the 6,000 years allowed by the Bible since the Creation was vastly inadequate for the sculpting of the current landscape by any natural mechanism; and the biologists who were just beginning to study the history of life via the fossil record were not far behind them. Around the turn of the nineteenth century, the French zoologist Jean-Baptiste Lamarck began to argue that fossil molluscan lineages from the Paris Basin had undergone structural change over time, and that the species concerned were consequently not fixed. Importantly, he implicated adaptation to the environment as the cause of change, although the means he suggested – subsequently infamous as “the inheritance of acquired characteristics” – brought later opprobrium.

Like every one of the many millions of other organisms with which we share our planet, the species Homo sapiens is the product of a long evolutionary history. The first very simple cellular organisms spontaneously arose on Earth close to four billion years ago, and their descendants have since diversified to give us forms as different as streptococci, roses, sponges, anteaters, and ourselves.

While it isn’t necessary to do so, it’s often good to start a book by saying something that is clearly true. So, let’s do that. Science has had (and continues to have) a significant impact upon our lives. This fact is undeniable. Science has revealed to us how different species arise, the causes of our world’s changing climate, many of the microphysical particles that constitute all matter, among many other things. Science has made possible technology that has put computing power that was almost unimaginable a few decades ago literally in the palms of our hands. A common smartphone today has more computing power than the computers that NASA used to put astronauts on the Moon in 1969! There are, of course, many additional ways in which science has solved various problems and penetrated previously mysterious phenomena. A natural question to ask at this point is: why discuss this? While we all (or at least the vast majority of us!) appreciate science and what it has accomplished for modern society, there remain – especially among portions of the general public – confusions about science, how it works and what it aims to achieve. The primary goal of this book is to help address some specific confusions about one key aspect of science: how it explains the world.

Once upon a time it was fair to say that most people knew little of science. After all, scientists spent years learning their job so it’s clearly tough-going and, by and large, the rest of the world could get by knowing nothing of superconductivity or the origins of the universe. But increasingly our daily lives have come to be dominated by science, and part of that revolution has been the ever-expanding reach of television and the Internet as sources of information. It’s as though, unwittingly, we’ve all signed up to the Open University. And, it should be said, when it comes to science this has all been helped by a growing awareness among those in the trade that they have an obligation to let the world know how they while away their days.

Early hominins were not limited to particular sites or localities in a paleontological or archeological sense, but lived and died in complex and dynamic landscapes and ecosystems of which we have partial, incomplete records. The fossil evidence of early hominin paleoenvironments is always limited, sometimes providing brief snapshots of small areas, other times affording very coarse chronological and spatial resolution over large distances. Taphonomic conditions typically vary within any one locality over time, and from one locality to another. And yet, it is these partial and biased records that we use to build an understanding of the forces that have shaped our evolution.